There was a high number of rejected ballot papers

Ron Gould has been involved with more than 100 election observation missions.

It has been estimated that more than 100,000 votes were discounted in the May poll, mainly because of errors in the way they had been completed.

Mr Gould will also focus on the electronic counting process and the arrangements for postal voting.

Although the Electoral Commission has a statutory duty to report on the Holyrood poll, it will also report on the council elections following a request from the Scottish Executive.

I hope my review will help ensure that the people of Scotland can be confident that any lessons are learned for the future Ron Gould Elections expert

Mr Gould, who has also advised the United Nations, said: "I look forward to working with all those involved in the Scottish elections to enable us to develop a clear picture of exactly what happened and why.

"Democracy depends on public confidence in elections.

"I hope my review will help ensure that the people of Scotland can be confident that any lessons are learned for the future."

The review will also look into the decisions to hold the parliamentary and local government polls on the same day, combining the two parliamentary votes on one ballot sheet and the role of the Electoral Commission itself in preparations for the elections.

Electoral Commission chairman Sam Younger said: "Ron Gould is widely respected as one of the world's leading elections experts and he will undertake a thorough and independent review of all aspects of the elections in Scotland, including those areas where the law gives the commission itself a role."

A spokesman for the Scotland Office added: "We welcome the announcement that an independent electoral expert will lead the review into the 2007 Scottish elections.